Gerry Adams has named a number of senior Sinn Féin figures suspected of the 1983 murder of prison officer Brian Stack in an email sent to Garda Commissioner Nóirín O'Sullivan.

Three of those named by the Sinn Féin President are well-known politicians, while a fourth man is a suspected former IRA boss, the Irish Independent can reveal.

In the email to Ms O'Sullivan, Mr Adams claims he was supplied the names by the victim's son, Austin Stack, and that was passing them on "in order to remove any uncertainty".

However, Mr Adams is facing serious questions after Mr Stack last night insisted he never provided names to the Sinn Féin President.

The email was sent three days before the General Election - and has now been passed on to detectives investigating the brutal killing.

The three politicians are household names and are currently serving. The fourth man is suspected of having held a very senior role in the IRA, and is currently facing other charges that are unrelated to IRA membership.

Brian Stack. Photo: PA

The decision by Mr Adams to name party colleagues in connection with a serious crime is highly unusual. It is understood gardaí will interview a number of those included.

Austin Stack, who is the deputy governor at Portlaoise Prison, gave a fresh statement to gardaí on Wednesday.

He told the Irish Independent last night that by naming senior Sinn Féin figures, Mr Adams and his party have "very serious questions to answer in relation to a live murder inquiry".

He said that in any other organisation, the individuals named by Mr Adams would have been suspended pending the investigation's outcome.